The presence of organophosphate esters (OPEs) in industrial and agricultural drain waters, spills, runoffs, and drifts, as well as OPE agent-based chemical munitions that may be released during warfare or a terrorist attack, poses great risks to human health and the environment. The worldwide number of exposures to OPEs in pesticides and insecticides is estimated at some 3,000,000 per year; the resulting total number of deaths and casualties is estimated at over 300,000 per year. Eyer, P. “The role of oximes in the management of organophosphorus pesticide poisoning,” Toxicol Rev. 2003, 22(3), 165-190. Numerous OPE-based pesticides, insecticides and warfare agents, such as sarin, soman, and VX, in addition to being carcinogenic, act as nerve poisons which may cause cumulative damage to the nervous system and liver. The primary mechanism of action of the OPEs is irreversible inhibition of acetylcholinesterases; essential enzymes for breaking down acetylcholine and maintaining normal nerve function, resulting in the accumulation of the neurotransmitter acetylcholine at nerve synapses. Structures of the nerve poison sarin and a model analogue used in this study, diisopropyl fluorophosphate (DFP), are given in FIG. 1. The acute toxicity of various pentavalent organophosphorus (OP) compounds toward living species has resulted in the widespread use of phosphoric, thiophosphoric, and phosphonothioic acid derivatives as biocides for animal and crop protection as well as in the development of chemical weapons of mass destruction. Quin, L. D. A Guide to Organophosphorus Chemistry; Wiley: New York, 2000; Compton, J. A. Military Chemical and Biological Agents; Telford Press: NJ, 1997; p 135; Gallo, M. A.; Lawryk, N.J. Organic Phosphorus Pesticides. The Handbook of Pesticide Toxicology; Academic Press: San Diego, Calif., 1991; Sultatos, L. G., J. Toxicol. Environ. Health, 1994, 43(3), 271-289; Morales-Rojas, H.; Moss, R. A., Chem. Rev, 2002, 102(7), 2497-2522. Development of an economical strategy for dealing with possible OP contamination is critical.
Some of the first OPE-decontaminating agents were oxidizers, such as bleaching powders. See Yang, Y. C. et al. “Decontamination of chemical warfare agents,” Chem. Rev. 1992, 92(8), 1729-1743. However, the activity of bleaches decreases upon long-term storage; therefore, to have the desired effect, copious amounts of bleach must be used. Moreover, because bleaches are corrosive, they are not compatible with many surfaces.
At present, the decontamination solutions of choice are DS-2 (a non-aqueous liquid composed of diethylenetriamine, ethylene glycol, monomethyl ether, and sodium hydroxide) and STB (super tropical bleach). Although DS-2 is generally not corrosive to metal surfaces, it damages skin, paints, plastics, rubber, and leather materials. STB, while effective, has the same environmental problems as bleaches and cannot be used on the skin. Consequently, personal decontamination equipment typically consists of packets of wipes containing such chemicals as sodium hydroxide, ethanol, and phenol. These chemicals are selected to provide a nucleophilic attack at the phosphorous atom of nerve agents.
Efforts aimed at alternatives to oxidizers have focused on the development of processes for the catalytic destruction (CD) of nerve agents and pesticides. Chiron, S. et al. “Pesticide chemical oxidation: state-of-the-art,” Water Research 2000, 34(2), 366-377; and Russell, A. J. et al. “Biomaterials for mediation of chemical and biological warfare agents,” Annu. Rev. Biomed. Eng. 2003, 5, 1-27. It was first recognized in the 1950s that certain metal ions, especially Cu(II), had the ability to catalyze the hydrolysis of nerve agents and their stimulants. The catalytic activity of such chemicals was significantly enhanced when Cu(II) was bound to certain ligands. For example, diisopropyl phosphorofluoridate (DFP) has a hydrolytic half-life of approximately 2 days in water, 5 hours in water when CuSO4 is added, and just 8 minutes in water when Cu(II) bound to either histidine or N,N′-dipyridyl is added in an approximately 2:1 ratio of metal complex to substrate. Sarin was found to be even more susceptible to metal-based catalysis with a half-life of only 1 minute in the presence of tetramethyl-EDA-Cu(II) complex (1:1 metal complex to substrate). However, the use of free copper-ligand complexes for catalyzing the degradation of nerve agents also has disadvantages. First, the nerve agent must be brought into contact with a solution of the metal-ion-containing catalyst. Second, the ratio of metal to chelate must be carefully controlled. Third, solubility issues can still limit the pH range and choice of chelates for use in a particular environment. Catalytic hydrolysis is an important step in the detoxification of insecticides and chemical warfare agents; reactions show high specificity and dramatically enhanced rates.
In addition, researchers have begun to look at enzymes stabilized by attachment to a polymeric support as catalysts for the degradation of nerve agents. These enzymes, variously known as organophosphorous acid anhydrases, phosphotriesterases, sarinase, or others, are extracted either from microorganisms, such as Pseudomonas diminuta, or from squid. The enzymatic approach shows promise but is limited by the specificity of the proteins for their substrates, e.g., a parathion hydrolase would not be effective against another nerve agent. Further, the enzymes require a very specific range of conditions, e.g., pH, to function properly. In addition, field conditions can involve concentrated solutions of nerve agents, which can overwhelm the relatively low concentration of enzymes, which can be immobilized on a support.
The shortcomings of the free metal-ligand complexes and enzymatic approaches has caused the majority of the practical catalytic destruction technologies to focus on acid-catalyzed or base-catalyzed hydrolysis or nucleophile-aided hydrolysis. Magee, R. S. “U.S. chemical stockpile disposal program: the search for alternative technologies. In Effluents From Alternative Demilitarization Technologies,” ed. F W Holm, Dordrecht: Kluwer Acad., 1998, 22, 112; Amos, D.; Leake, B. “Clean-up of chemical agents on soils using simple washing or chemical treatment processes,” J. Hazard. Mater. 1994, 39, 107-117; Yang, Y. C. “Chemical detoxification of nerve agent,” Acc. Chem. Res. 1999, 32, 109-15; and Yang, Y. C.; Baker, J. A.; Ward, J. R. “Decontamination of chemical warfare agents,” Chem. Rev. 1992, 92(8), 1729-1743. In this regard, α-nucleophiles, such as hydroperoxides, hypochlorite, iodosocarboxylates, hydroxamates, and oximates, have been investigated alone or in concert with surfactants. Wagner, G. W.; Yang, Y.-C. “Rapid Nucleophilic/Oxidative Decontamination of Chemical Warfare Agents,” Ind. Eng. Chem. Res. 2002, 41(8), 1925-1928; Moss, R. A.; Chung, Y. C. “Immobilized iodosobenzoate catalysts for the cleavage of reactive phosphates,” J. Org. Chem. 1990, 55(7), 2064-2069; and Fanti, M.; Mancin, F.; Tecilla, P.; Tonellato, U. “Ester Cleavage Catalysis in Reversed Micelles by Cu(II) Complexes of Hydroxy-Functionalized Ligands,” Langmuir 2000, 16(26), 10115-10122. However, very few reagents are currently available that are both inexpensive and non-toxic as well as catalytic. Rather, most of these compounds show only stoichiometric dephosphorylating activities at neutral pH. Bhattacharya, S.; Snehalatha, K. “Evidence for the Formation of Acylated or Phosphorylated Monoperoxyphthalates in the Catalytic Esterolytic Reactions in Cationic Surfactant Aggregates,” J. Org. Chem. 1997, 62(7), 2198-2204. Notable exceptions include micellar iodosobenzoate, and related derivatives, micelle-forming metallocomplexes, and immobilized metal chelate complexes. Moss, R. A.; Chung, Y. C. “Immobilized iodosobenzoate catalysts for the cleavage of reactive phosphates,”J. Org. Chem. 1990, 55(7), 2064-2069; Menger, F. M.; Gan, L. H.; Johnson, E.; Durst, D. H. “Phosphate ester hydrolysis catalyzed by metallomicelles,” J. Amer. Chem. Soc. 1987, 109(9), 2800-2803; and Chang et al. (US 2003/0054949 A1). Most studies have concentrated on homogeneous or micellar catalysts, which do not afford the advantages of catalyst recycle. Additionally, operational cost and environmental footprint are always a concern.
Magnetic nanoparticles have attracted attention for possible applications to biological and environmental separations because they permit fast and economical removal of target compounds from complex media by use of magnetic fields. Magnetite nanoparticles are most commonly utilized and often prepared by co-precipitation of Fe(II) and Fe(III) salts in water. The procedure is simple and can be run on a large scale with “off the shelf” raw materials. Magnetic nanoparticles may also be functionalized by reactive groups and used as catalysts. Because the particles are small, the surface area per unit volume is high and mass transfer resistances are small.
Even given the advances discussed above, destruction of stockpiled chemical weapons and OPE biocides accumulated in the biosphere by environmentally friendly means remains challenging, calling for continuing development. Singh B K, Walker A. “Microbial degradation of organophosphorus compounds” FEMS Microbiol Rev. 2006, 30(3), 428-471; Russell A J, Berberich J A, Drevon G F, Koepsel R R. “Biomaterials for mediation of chemical and biological warfare agents,” Annu Rev Biomed Eng. 2003, 5, 1-27; Raushel F M. “Bacterial detoxification of organophosphate nerve agents,” Curr Opin Microbiol. 2002, 5(3), 288-295. As mentioned above, chemical means of OP decomposition by hydrolysis or oxidation are among the common decontamination techniques. Acid- or base-catalyzed hydrolysis or nucleophile-aided hydrolysis enable highly specific and efficient pathways of the OP decontamination. Magee, R. S. “U.S. chemical stockpile disposal program: the search for alternative technologies. In: Effluents From Alternative Demilitarization Technologies,” Holm, F. W., editor, Dordrecht: Kluwer Acad. 1998, 22, 112; Amos, D., Leake, B. “Clean-up of chemical agents on soils using simple washing or chemical treatment processes,” J. Hazard. Mater. 1994, 39, 107-117; Yang, Y. C. “Chemical detoxification of nerve agent,” Acc. Chem. Res. 1999, 32, 109-115; Yang, Y. C.; Baker, J. A.; Ward, J. R. “Decontamination of chemical warfare agents,” Chem. Rev. 1992, 92(8), 1729-1743; Wagner, G. W., Yang, Y.-C., “Rapid nucleophilic/oxidative decontamination of chemical warfare agents,” Ind. Eng. Chem. Res. 2002, 41(8), 1925-1928; Moss, R. A., Chung, Y. C. “Immobilized iodosobenzoate catalysts for the cleavage of reactive phosphates,”J. Org. Chem. 1990, 55(7), 2064-2069; Fanti, M., Mancin, F., Tecilla, P., Tonellato, U., “Ester cleavage catalysis in reversed micelles by Cu(II) complexes of hydroxy-functionalized ligands,” Langmuir 2000, 16(26), 10115-10122.
Interestingly, hypervalent iodine carboxylates, such as 2-iodoxybenzoic acid (IBX, 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide) and o-iodoso- or iodosylbenzoic acid (IBA) (Scheme 1) and their tautomers and derivatives, have attracted increasing interest because of their selective, mild, and environmentally friendly properties in organic reactions, such as oxidation of alcohols into carbonyl compounds, oxidation of thiols to disulfides, single electron-transfer agents in cyclization of unsaturated amines to heterocycles and amides to γ-lactams, cleavage of oximes and hydrazones into the corresponding carbonyl compounds, etc. E. B. Merkushev, “Organic Compounds of Polyvalent Iodine—Derivatives of Iodosobenzene,” Russ. Chem. Rev. 1987, 56 (9), 826-845; A. Varvoglis, “Hypervalent Iodine in Organic Synthesis,” Academic Press, San Diego (1997); Wirth, T. “IBX-new reactions with an old reagent,” Angew. Chem. Int. Ed. 2001, 40(15), 2812-2814.
Compounds classified as α-nucleophiles have strong hydrolytic reactivity, excellent chemical stability in the targeted complex systems, and relatively straightforward preparations. For example, hypervalent iodine carboxylates are very reactive α-nucleophiles due to the large electron density on the exocyclic oxygen and the short endocyclic I—O bond capable of attacking electrophilic P—O centers in the OPE compounds. Morales-Rojas, H.; Moss, R. A. “Phosphorolytic Reactivity of o-Iodosylcarboxylates and Related Nucleophiles,” Chem. Rev. 2002, 102(7), 2497-2522.

Moss and co-workers exploited the nucleophilic reactivity of hypervalent iodine carboxylates for the degradation of organophosphorus substrates. Moss, R. A., Chung, Y. C. “Immobilized iodosobenzoate catalysts for the cleavage of reactive phosphates,” J. Org. Chem. 1990, 55(7), 2064-2069; R. A. Moss, H. Morales-Rojas, “Kinetics of Cleavage of Thiophosphates and Phosphonothioates by Micellar Iodosocarboxylates and Copper Metallomicelles,” Langmuir 2000, 16(16), 6485-6491; Morales-Rojas, H.; Moss, R. A. “Phosphorolytic Reactivity of o-Iodosylcarboxylates and Related Nucleophiles,” Chem. Rev. 2002, 102(7), 2497-2522. Furthermore, it has been shown that reactivity of these agents can be improved by the reactant incorporation into the self-assembled colloids, such as surfactant micelles. Moss, R. A.; Morales-Rojas, H. Langmuir 2000, 16, 6485; Moss, R. A.; Kim, K. Y.; Swarup, S. J. Am. Chem. Soc. 1986, 108, 788; Morales-Rojas, H.; Moss, R. A. “Phosphorolytic Reactivity of o-Iodosylcarboxylates and Related Nucleophiles,” Chem. Rev. 2002, 102(7), 2497-2522. The rate enhancements observed in these aggregated systems are primarily due to the increases in the concentrations of reactants in the small interfacial volumes in which the reactions occur. Over the years, powerful reagents for the chemical degradation of the OPE compounds were created via syntheses of iodoso-modified surfactants and hydrophobic iodosocarboxylates with enhanced binding to the micellar pseudophase. C. A. Panetta, S. M. Garlick, H. Dupont Durst, F. R. Longo, J. R. Ward “Synthesis of 4-alkyl-2-iodosobenzoic acids: potent catalysts for the hydrolysis of phosphorus esters,” J. Org. Chem. 1990, 55(18), 5202-5205; R. A. Moss, R. Fujiyama, H. Zhang, Y. C. Chung, K. McSorley “Iodosobenzoate-microemulsion reagents for the cleavage of a reactive phosphate,” Langmuir 1993, 9(11), 2902-2906; Moss, R. A.; Morales-Rojas, H. “Kinetics of Cleavage of Thiophosphates and Phosphonothioates by Micellar Iodosocarboxylates and Copper Metallomicelles,” Langmuir 2000, 16(16), 6485-6491; R. A. Moss, K. Y. Kim, S. Swamp “Efficient catalytic cleavage of reactive phosphates by a functionalized o-iodosobenzoate surfactant,” J. Am. Chem. Soc. 1986, 108(4), 788-793. Polymers modified with covalently attached iodosobenzoate groups have also been synthesized for the purpose of creating solid decontaminates and were reported to be capable of inducing the cleavage of the P—O bond. Moss, R. A.; Bolikal, D.; Durst, H. D.; Hovanec, J. W. Tetrahedron Lett. 1988, 29, 2433; Moss, R. A.; Chung, Y.-C.; Durst, H. D.; Hovanec, J. W. J. Chem. Soc. Perkin Trans. 1 1989, 1350; Moss, R. A.; Chung, Y.-C. J. Org. Chem. 1990, 55, 2064; R. A. Moss, Y.-C. Chung “An Efficient Iodosobenzoate-Functionalized Polymer for the Cleavage of Reactive Phosphates” Langmuir 1990, 6, 1614-1616. Polymer-supported iodoxybenzoic acid has also been utilized as a reagent for alcohol oxidation and OP hydrolysis. M{umlaut over (ú)}lbaier, M., Giannis, A., “The synthesis and oxidative properties of polymer-supported IBX,” Angew. Chem. Int. Ed. 2001, 40(23), 4393-4394; Z. Lei, C. Denecke, S. Jegasothy, D. C. Sherrington, N. K. H. Slater and A. J. Sutherland, “A facile route to a polymer-supported IBX reagent,” Tetrahedron Lett. 2003, 44(8), 1635-1637; Morales-Rojas, H.; Moss, R. A. “Phosphorolytic Reactivity of o-Iodosylcarboxylates and Related Nucleophiles,” Chem. Rev. 2002, 102(7), 2497-2522.
Immobilization of iodoso- and iodoxybenzoate reagents into paints, synthetic fabrics and other colloidal systems can result in self-decontaminating materials. R. A. Moss, Y. C. Chung, “Immobilized iodosobenzoate catalysts for the cleavage of reactive phosphates,” J. Org. Chem. 1990, 55(7), 2064-2069. Moss and Chung reported iodosobenzoate catalysts immobilized onto macroreticular acrylate resin with pending dimethylamino groups, which mimicked a micellar catalyst and exhibited reactivity comparable to aqueous micellar suspensions. Moss, R. A.; Chung, Y.-C. J. Org. Chem. 1990, 55, 2064.; R. A. Moss, Y.-C. Chung “An Efficient Iodosobenzoate-Functionalized Polymer for the Cleavage of Reactive Phosphates,” Langmuir 1990, 6, 1614-1616. Numerous reported synthetic routes toward IBA and IBX moiety immobilization included (but were not limited to) silylation of silica or titanium dioxide followed by coupling with dimethylamine iodobenzoate derivative with the subsequent oxidation of the iodo- to iodoso-reagents, coupling of hydroxy-iodobenzoic acid to an aminoalkyl-derivatized macroporous resin, chloromethyl polystyrene, or silica gel via an aryl ether or phenoxide linkers, modification of nylon into aminonylon, which could be further quaternized with iodobenzoate, leading to the quaternary ammonium iodobenzoate nylon derivative, or quaternization of dimethylamino groups of a commercially available resin by iodobenzoate moieties followed by their oxidation to iodosobenzoate groups. R. A. Moss, Y. C. Chung, “Immobilized iodosobenzoate catalysts for the cleavage of reactive phosphates,” J. Org. Chem. 1990, 55(7), 2064-2069; R. A. Moss, Y.-C. Chung “An Efficient Iodosobenzoate-Functionalized Polymer for the Cleavage of Reactive Phosphates,” Langmuir 1990, 6, 1614-1616; M{umlaut over (ú)}lbaier, M., Giannis, A., “The synthesis and oxidative properties of polymer-supported IBX,” Angew. Chem. Int. Ed. 2001, 40(23), 4393-4394; Sorg, G., Mengel, A., Jung, G., Rademann, J. “Oxidizing polymers: a polymer-supported, recyclable hypervalent iodine (V) reagent for the efficient conversion of alcohols, carbonyl compounds, and unsaturated carbamates in solution,” Angew. Chem. Int. Ed. 2001, 40(23), 4395-4397; Reed, N. N., Delgado, M., Hereford, K., Clapman, B., Janda, K. D., “Preparation of soluble and insoluble polymer supported IBX reagents,” Bioorg. Medicinal Chem. Lett. 2002, 12, 2047-2049; Togo, H.; Sakuratani, K. “Polymer-supported hypervalent iodine reagents,” Synlett 2002, 12, 1966-1975; Ladziata, U., Willging, J., Zhdankin, V. V. “Facile Preparation and Reactivity of Polymer-Supported N-(2-Iodyl-phenyl)-acylamide, an Efficient Oxidizing System,” Org. Lett. 2006, 8(1), 167-170.
However, all of the approaches described above were multistep syntheses involving either careful choice or extensive chemical derivatization of a surface prior to the conjugation of an iodocarboxylate moiety, for example. Therefore, needed is a method of derivatizing substrates to enable them to decompose organophosphate agents, without the need for extensive pretreatment of the substrate prior to derivatization.